The present invention is directed to a valve for a tracheostomy tube and, more specifically, to a speaking valve having substantially unrestricted linear air flow through the valve.
Patients who have experienced tracheostomy and the insertion of a tracheostomy tube frequently have difficulties in their perceptual speech because the exhaled air does not produce sufficient vibratory movement of the vocal cords. This is very disturbing to the patient, the patient""s family and healthcare personnel. The problem has been recognized for many years and the applicants are aware of efforts to provide a tracheostomy tube with improved speech characteristics. Many of these tubes have controlled air leaks, additional cuffs, pneumatic vibrators, springs, diaphragms and valve flaps. Other tubes have a valve with a moving ball such as disclosed in the following U.S. patents.
UK Patent No. 1 217 554, Dec. 31, 1970 and German Patent No. DE 3436-777-A, Apr. 25, 1985 also disclose a moving ball speech valve. A moving ball speaking valve is further disclosed in xe2x80x9cOtolaryngology-Head and Neck Surgeryxe2x80x9d, pages 103-107, Jul. 2000, xe2x80x9cNew Unidirectional Airflow Ball Tracheostomy Speaking Valvexe2x80x9d, Shikani, French and Siebens.
One major factor which has not received much attention in the design and fabrication of tracheostomy tubes is the flow of air within the cannula and the valve. An interface occurs at the end of the cannula exteriorly of the patient. The two dimensional orifice, having no length, restricts the free flow of room air into the cannula. The pressure drop across the orifice is the pressure necessary for a given flow rate through the cannula. The conventional orifice is not efficient because only the air in the immediate vicinity of the opening is drawn into the cannula. A mismatch occurs between the room air and the cannula and there is a further increase in the pressure required for a given flow rate. Further, any discontinuity inside the cannula can be viewed as an orifice which adds to the pressure necessary for the flow of air through the cannula. The discontinuity may be irregularities on the inner wall. When a flapper valve is connected to the end of the cannula the valve housing has a linear effect on the impedance but the flap, by its spring-like nature, adds a non-linear increase to the impedance of the system. This increase of impedance to inhalation is most noticeable at low flow rates. This is also true with disk valves. This effect can be greatly reduced by making the flap or disk larger resulting in an increase in the housing size. This would make the valve too unwieldy to be practical. The ball valve by its nature is more compact since its outside diameter can be much smaller than the flapper or disk valves. The problem with the ball valve is that, in its simplest form, at least two additional interfaces are created which add to the system impedance on inspiration. Unlike the flapper or disk valves this effect can be minimized without increasing the outside diameter of the valve. The present invention is directed to solving this problem.
Despite the efforts to date, there is still a problem to provide a tracheostomy tube with good speech characteristics.
It is an object of the present invention to provide a speaking valve for a tracheostomy tube which offers reduced air resistance and enhances clarity and ease of speech by the patient.
It is a further object of the present invention to provide a tracheostomy tube with a speaking valve which has an unextended profile and has minimal visibility.
In accordance with the teachings of the present invention, there is disclosed a valve in combination with a tracheostomy tube, the tube having a first open end adapted to protrude from the throat of a patient. A cylindrical body having an outer diameter is snugly received within the first end of the tracheostomy tube. A retaining means is disposed within the cylindrical body distal from the first open end of the tube. A ball is disposed between the first open end of the tube and the retaining means. Seating means for the ball is disposed at the first open end of the tube. Guiding means are formed within the tracheostomy tube to maintain the ball substantially centered within the tracheostomy tube wherein air flow about the ball is unrestricted. When the patient exhales, due to the unrestricted air flow, minimum force is required to move the ball against the seating means to seal the opening in the first end of the tube and prevent exhaled air from exiting the tracheostomy tube forcing air through the larynx, and when the patient inhales, the ball is moved away from the seating means in the first end of the tube and retained by the retaining means wherein air enters the tracheostomy tube.
In further accordance with the teachings of the present invention, there is disclosed a hollow tracheostomy tube adapted to be received in the throat of a patient. The tracheostomy tube has a first end protruding from the neck of the patient and a second end extending into the trachea of the patient below the larynx. The improvement is a speaking valve having a cylindrical body having a first end. A flange is formed circumferentially about the first end of the body such that the cylindrical body is received in the first end of the tracheostomy tube with a friction fit. The flange on the body holds the valve at the first end of the body. A retaining means is disposed within the body distal from the flange. An opening is formed in the flange. A ball is disposed between the opening and the retaining means. A plurality of circumferentially spaced-apart ribs are formed in the body of the speaking valve, each rib being approximately perpendicular to the flange. The ball is guided by the ribs. The ball is substantially centered within the tracheostomy tube wherein linear air flow around the ball is unrestricted. The air moves at constant velocity when the patient inhales and exhales, the ball moving between the opening in the flange and the retaining means.
In still further accordance with the teachings of the present invention, there is disclosed a hollow tracheostomy tube adapted to be received in the throat of a patient. The tracheostomy tube has a first end having an opening and protruding from the neck of the patient and a second end extending into the trachea of the patient below the larynx. The improvement is a retaining means disposed within the tracheostomy tube near the first end of the tube. A ball is disposed on the plurality of circumferentially spaced-apart ribs and guided on the ribs. Air flow around the ball is unrestricted
In yet further accordance with the teachings of the present invention, there is disclosed a tracheostomy tube including a cannula provided with a speaking valve assembly having a floating ball therein. The ball is guided for limited longitudinal movement within the speaking valve assembly. The air flow around the ball is at a substantial constant velocity, thereby substantially reducing the force required to be exerted by the patient to close the speaking valve assembly during exhalation, and thereby quickly activating the patient""s vocal cords for clearer and easier patient speech.
These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings.